Switch key



NOV. 4, 1941. F.. Q NEVslUs 2,261,809

SWITCH KEY Filed DSG. 5, 1939 INVENTOR FRANCIS O.NESIUS ATTORNEY.

Patented Nov. 4, 1941 UNITED STATES PATENT OFFICE SWITCH KEY of New York Application December 5, 1939, Serial No. 307,649

(Cl. 20G- 1) 7 Claims.

This invention relates to switch keys particularly adapted for use with telephone switchboards.

Manufacturers of two-way telephone switch keys have been confronted with the problem of preventing the switch lever from over-riding its center position on being released from one of its operating or switching positions. If the switch lever were free to pass its center position on being released from one switching position it might accidentally make or break the contacts between the switch springs at the other switching posi tion of the switch. To prevent over-riding, it has been the practice to form the ends of certain of the switch springs, which are engaged and fieXed by the switch lever, into various configurations such as loops which tend to prevent rapid release of the switch lever from its switching positions and thus keep the inertia of the switch lever as it approaches its central position at a minimum. While the known constructions have accomplished their purpose they have several disadvantages. Due to the peculiar configuration of these looped springs the strain from the repeated distortion of the looped portion of the spring is more or less concentrated in a limited region of the spring with the result that the life of the springs is usually shorter than the remaining elements of the switch key. Further, since these springs are a part of the switch spring assemblies it is necessary to disassemble a spring assembly to replace a broken or weakened spring.

It is accordingly a purpose of the present invention to provide an improved switch key with a buffer spring or springs incorporated therein to prevent the switch lever from passing its center position, when released from either of its switching positions, and thereby accidentally making or breaking contacts at the opposite position.

It is therefore an object of the invention to provide a switch key in which the buffer spring is mounted independently of the switch spring assemblies and which may be readily replaced without disturbing the switch springs.

It is another object of the invention to provide a switch key in which the strain on the buffer spring is distributed throughout substantially the entire length of the spring.

These and other objects of the invention will appear from the detailed description and claims when taken with the drawing in which:

Figs. 1 and 2 are side and edge views respectively of an improved switch key made in accordance with the present invention;

Fig. 3 is a vertical section taken on line 3--3 of Fig. 1 and illustrating certain details of thev construction of the improved switch key; and

Figs. 4 and 5 are face and edge views respectively of one of the frame plates forming a part of the present switch key.

Referring to the drawing, reference character 5 generally indicates a switch key made in accordance with the present invention. This key comprises a pair of frame plates B, which may be identical in shape, each having an aperture I and a struck out lug 8. The frame plates are secured in face to face relation as shown particularly in Fig. 2 with the lug 8 of each plate seating in the aperture 'I of the other plate whereby the plates are maintained in proper registry. The upper part 9 of each plate is offset as shown in Figs. 2 and 5 which provides, when the plates are assembled, a space within which the switch lever IIl is free to move. This lever is provided with a handle II at its upper end and is pivoted intermediate its ends on the pin I2 extending between the outwardly bowed strips I3 of the frame plates. A tubular bushing I4 xed to the lever receives the pin I2 which is supported in apertures I5 in the frame plates but preferably is fixed to only one of the frame plates to facilitate dismantling of the switch key.

As shown particularly in Figs. l and 4 the upper part of each frame plate is cut out to provide clearance for the switch spring operating rolls IB rotatably carried by the shaft Il on each side of the lower end of the switch lever. The lugs I8 integral with the frame plate and projecting into the cutout portion thereof cooperate with the stops I9 on the switch lever to limit the movement of the lever about the pin I2.

The upper end of each frame plate is bent outwardly to provide right angular fastening flanges v2l! having threaded apertures which receive the screws ZI extending through the slotted top plate 22. These iianges are provided with short pins 23 which depend from the lower surface thereof.

g These pins engage in holes (not shown) Provided gagement of these springs with the rolls IB is such that the switch lever Il) is prevented from moving by its own inertia beyond its central position (Fig. l) when it has been released from either of its operating positions.

The switch spring assemblies 26 comprising the springs 27 having the usual contacts 28 are insulatedly carried on mounting blocks 29 at each side of the frame plate assembly. These mounting blocks are shaped to be secured in the openings 3G and 3| in the frame plates as shown in Fig. 3. A screw 32 extending thru a hole 33 in one of the blocks and holes 34 in the frame plates is threaded into the hole 35 in the other block to clamp the blocks to the frame plates and to maintain the frame plates in face to face relation. It will be understood that the lower ends 36 of the switch springs 27 are connected in the usual manner in the telephone circuits to be controlled by the switch key.

In the present embodiment of the invention as shown in Fig. l, the upper end of the master or motor spring 3l of each spring assembly terminates in an angular portion 38 which engages the adjacent roll l5. It will be seen from the construction thus far described, that on shifting the rolls i6 by moving the upper end of the switch lever to the right or to the left as viewed in Fig. l, the rolls will force either the two left or the two right motor springs 3l to break the contact with the inner switch springs and to make contact with the outer switch springs. The limiting stops i9 in the embodiment illustrated are spaced a suiiicient distance from the rolls IS to permit the lever and rolls to be shifted to locked switching positions, that is, when the handle ll is moved to the extreme left or to the extreme right it will remain in that position until manually released. However, the switch key may be of the non-locking type by having the limiting stops i9 closer together.

On manually releasing the key from either of its switching positions the motor springs which have been deflected, move the lever to its central position (Fig. l) and the inertia of the lever and rolls tends to cause them to move past this central position. However, the buiier springs 24 which frictionally engage the rolls act as a brake to overcome this inertia and prevent the key from accidentally displacing the switch springs on the side opposite from the released position of the switch. It will be noted that the force, exerted by the motor springs 31 against the rolls I6 when they are released from a switching position, decreases as the lever approaches its central position and that the bumped portion of the buffer springs causes the counter force exerted by the buffer springs against the rolls to increase as the lever approaches its central position. The result of the decreasing force of the deflected motor springs and the increasing force of the buffer springs on release of the lever from a switching position is to cause practically all of the inertia of the lever and rolls to be absorbed by the time the lever reaches its central position (Fig. l), thus preventing over-riding of the lever a distance sufficient to make or break the switch contacts on the other side of the key.

The present construction provides a switch key which may be readily assembled and disassembled by removing the single screw 32. rfhe distortion of the buffer springs during operation of the key is distributed throughout the length of the springs so that the strain is not concentrated at a single region thereof with the result that the life of the spring is relatively great. Further, these springs may be easily replaced without dismantling the key whereas heretofore the springs which were designed to accomplish the same purpose as the present spring have been incorporated in the switch spring assemblies necessitating dismantling of the spring assemblies when it was necessary to replace a roken or weakened spring.

What I claim is:

1. A switch key comprising a frame, a group of switching elements carried by said frame, a lever pivotally mounted on said frame, said lever being movable trom a normal position to a switching position to deiiect one of said elements relative to another element of the group, a bowed spring supported at its ends on said frame at opposite sides of the pivotal mounting of said lever, said spring continuously engaging said lever to retard the return of said lever from said switching position to said normal position.

2. A switch key comprising a frame, a lever pivoted on `said frame, a roll carried on said lever, spaced groups of switch springs supported on said frame, one spring of each group being disposed in operative relation to said roll, said lever and roll being movable from a central position to selectively deect said one spring of each group to a switching position, and a buffer spring supported at its ends on said frame at points symmetrically located with respect to the path of movement of said roll, said buffer spring continuously engaging said roll to retard the motion of said lever on release of a deiiected spring from a switching position.

3. A switch key comprising a frame, a switch spring assembly including a motor spring supported on said frame, a lever pivoted on said frame and shift-able from a central position to a switching position, said lever having a part to deiiect said motor spring as said lever is shifted from said central position to said switching position, a buier spring anchored to said frame at points spaced an equal distance at opposite sides of said pivot, a portion of said buffer spring extending along the plane of movement of the lever into the path of said part and engaging said part at said central position whereby said buiier spring overcomes the inertia of said lever as it is released from said switching position and returns to said central position.

4. A switch key comprising a frame, a switch spring assembly including a motor spring carried by said frame, a lever disposed in operative relation to said motor spring, said lever being pivotally mounted on said frame and being shiftable from a central position to a switching position, said lever having a part to deect said motor spring as said lever is shifted to said switching position, spaced fastening means carried by said frame at opposite sides of the pivotal mounting of said lever, a buffer spring having the ends thereof attached to said frame by said fastening means and at least a portion of said buffer spring extending into the path of said part and frictionally engaging said part at said central position to control the return of said lever from switching position to said central position.

5. A switch key comprising a frame, switch spring assemblies mounted in spaced relation on said frame, said spring assemblies each including a motor spring, a lever pivotally mounted on said frame and shiftable from a central position to opposite switching positions, said lever having a member thereon disposed in operative relation to said motor springs to selectively deflect the same as said lever is shifted to said switching positions, a buiTer spring extending in a direction common to the plane of movement of said lever and having its ends secured to the frame at points symmetrically located with respect to said motor springs, an intermediate portion of said spring extending into the path of said member and frictionally engaging said member at said central position to control the return of said lever from a switching position to said central position.

6. A switch key comprising a frame, switch spring assemblies mounted in spaced relation on said frame, said spring assemblies each including a motor spring, a lever pivotally mounted on said frame and shiftable from a central position to opposite switching positions, said lever having a member thereon disposed in operative relation to said motor springs to selectively deect the same as said lever is shifted to said switching positions, a buffer spring having its ends secured to said frame at points symmetrically located with respect to said motor springs, said buffer spring being generally curved and extending into the path of said member, said buffer spring having a humped portion at an intermediate part thereof to project toward and to engage said member at said central position, said buier spring frictionally engaging said member as it is shifted from said central position to a switching position, said humped portion preventing the lever from accidentally engaging one of said motor springs on being released from switching engagement with the other motor spring.

7. A switch key comprising a frame, a lever pivotally mounted on said frame, spaced switch springs carried by said frame, a portion of said lever being disposed between said switch springs, said lever being movable from a central position to deflect one or the other of said springs selectively to a switching position, a buier spring anchored at its ends on said frame in symmetrical relation to said switch springs in a position to continuously engage said lever, said buffer spring acting to prevent the accidental displacement of one of said switch springs by said lever when it releases the other switch spring from switching position.

FRANCIS O. NESIUS. 

